The following documents are considered herein:                [Non-Patent Document 1] International Business Machines Corporation (US), “Web Services Security (WS-Security)” [online], [searched on Apr. 1, 2004], the Internet <URL:        
http://www-106.ibm.com/developerworks/webservices/library/ws-secure/>                [Non-Patent Document 2] M. Terauchi, Y. Yamaguchi, A. Nishikai, T. Itoh, “Lightweight Implementation of Web Services and Web Services Security by Serial Processing,” “Symposium on Cryptography and Information Security” Collection of Manuscripts of Lecture at Institute in 2004, Jan. 27, 2004, pp. 119-124        
Web Services security includes specifications targeted for application of digital signature or encryption to a SOAP message or for propagation of a security token (see Non-Patent Document 1). Here, consideration will be made on a case where a message with the Web Services security adopted thereto is sent from a mobile device to a server and a message from the server is received by the mobile device. According to Non-Patent Document 2, typical procedures on the mobile device side in this case are as follows.
(Construction (Generation) of Message)
    Step 1: Construct a SOAP message    Step 2: Apply digital signature and encryption to the SOAP message    Step 3: Construct a SOAP header including information necessary for verifying the digital signature and for decrypting the encrypted value, a security token, and the like, and insert the information into the SOAP message(Communication)    Step 1: Establish communication with a server    Step 2: Send the SOAP message to the server    Step 3: Receive the SOAP message from the server    Step 4: Terminate the communication with the server(Decrypting Received Message)    Step 1: Decrypt a SOAP header located in the received SOAP message and accumulate information necessary for verifying digital signature and for decrypting the encrypted value    Step 2: Perform verification of the digital signature and decryption of the encrypted value in accordance with the order of description of the SOAP header    Step 3: Upon completion of the verification and decryption, extract a response from the server in the SOAP message and return the response to an application
Speeding up of the Web Service is an important issue not only for mobile devices but also for servers side. As a conventional technique for improving this issue, streaming XML processing is conceivable as disclosed in Non-Patent Document 2. However, there are also other factors left concerning long processing time except the XML processing. Accordingly, the problem of speeding up the Web Service has not yet been resolved completely. To be more precise, (a) calculation of a signature value in transmission of a message, and (b) decryption of a key upon reception of a message account for a very large portion of the processing time for security computation. Moreover, communication processing also accounts for a very large portion in the case of a wireless device.
Security processing by a pervasive device tends to require a very large amount of calculation time due to constraints of hardware, and of programming languages and the like. According to measurement conducted by a partner division of the inventors, it is learned that (a) calculation of the signature value by a sender side using a public key method, and (b) decryption of an encrypted value by a receiver side using the public key method, in particular, require the calculation time of several seconds for each step of processing.
Moreover, it is also known that a wireless device has a specific problem of consumption of a large amount of time in communication. As a result of measurement by the inventors, it is apparent that establishment of communication with a server, and processing for transmission and reception of a message require the processing time of several seconds to nearly a dozen or so seconds in total.
As a result of simple calculation using these values, when the Web Services security is adopted to a mobile device, the above-described procedures of (Construction (generation) of message), (Communication), and (Decrypting received message) require the total time in the range from about 15 to 30 seconds. Accordingly, it is apparent that speeding up thereof is an important issue.